package system2021.src.class06heap;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.TreeMap;

public class Code01_Comparator {

    public static void printStudents(Student[] students) {
        for (Student student : students) {
            System.out.println("Name : " + student.name + ", Id : " + student.id + ", Age : " + student.age);
        }
    }

    public static void printArray(Integer[] arr) {
        if (arr == null) {
            return;
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }

    public static void main(String[] args) {

        Integer[] arr = {5, 4, 3, 2, 7, 9, 1, 0};

        Arrays.sort(arr, new AComp());

        for (int i = 0; i < arr.length; i++) {
            System.out.println(arr[i]);
        }

        System.out.println("===========================");

        Student student1 = new Student("A", 4, 40);
        Student student2 = new Student("B", 4, 21);
        Student student3 = new Student("C", 3, 12);
        Student student4 = new Student("D", 3, 62);
        Student student5 = new Student("E", 3, 42);
        // D E C A B

        Student[] students = new Student[]{student1, student2, student3, student4, student5};
        System.out.println("第一条打印");

        Arrays.sort(students, new IdShengAgeJiangOrder());
        for (int i = 0; i < students.length; i++) {
            Student s = students[i];
            System.out.println(s.name + "," + s.id + "," + s.age);
        }

        System.out.println("第二条打印");
        ArrayList<Student> studentList = new ArrayList<>();
        studentList.add(student1);
        studentList.add(student2);
        studentList.add(student3);
        studentList.add(student4);
        studentList.add(student5);
        studentList.sort(new IdShengAgeJiangOrder());
        for (int i = 0; i < studentList.size(); i++) {
            Student s = studentList.get(i);
            System.out.println(s.name + "," + s.id + "," + s.age);
        }
        // N * logN
        System.out.println("第三条打印");
        student1 = new Student("A", 4, 40);
        student2 = new Student("B", 4, 21);
        student3 = new Student("C", 4, 12);
        student4 = new Student("D", 4, 62);
        student5 = new Student("E", 4, 42);
        TreeMap<Student, String> treeMap = new TreeMap<>((a, b) -> (a.id - b.id));
        treeMap.put(student1, "我是学生1，我的名字叫A");
        treeMap.put(student2, "我是学生2，我的名字叫B");
        treeMap.put(student3, "我是学生3，我的名字叫C");
        treeMap.put(student4, "我是学生4，我的名字叫D");
        treeMap.put(student5, "我是学生5，我的名字叫E");
        for (Student s : treeMap.keySet()) {
            System.out.println(s.name + "," + s.id + "," + s.age);
        }

    }

    public static class Student {
        public String name;
        public int id;
        public int age;

        public Student(String name, int id, int age) {
            this.name = name;
            this.id = id;
            this.age = age;
        }
    }

    // 任何比较器：
    // compare方法里，遵循一个统一的规范：
    // 返回负数的时候，认为第一个参数应该排在前面
    // 返回正数的时候，认为第二个参数应该排在前面
    // 返回0的时候，认为无所谓谁放前面
    public static class IdShengAgeJiangOrder implements Comparator<Student> {

        // 根据id从小到大，但是如果id一样，按照年龄从大到小
        @Override
        public int compare(Student o1, Student o2) {
            return o1.id != o2.id ? (o1.id - o2.id) : (o2.age - o1.age);
        }

    }

    public static class IdAscendingComparator implements Comparator<Student> {

        // 返回负数的时候，第一个参数排在前面
        // 返回正数的时候，第二个参数排在前面
        // 返回0的时候，谁在前面无所谓
        @Override
        public int compare(Student o1, Student o2) {
            return o1.id - o2.id;
        }

    }

    public static class IdDescendingComparator implements Comparator<Student> {

        @Override
        public int compare(Student o1, Student o2) {
            return o2.id - o1.id;
        }

    }

    // 先按照id排序，id小的，放前面；
    // id一样，age大的，前面；
    public static class IdInAgeDe implements Comparator<Student> {

        @Override
        public int compare(Student o1, Student o2) {
            return o1.id != o2.id ? o1.id - o2.id : (o2.age - o1.age);
        }

    }

    public static class MyComp implements Comparator<Integer> {

        @Override
        public int compare(Integer o1, Integer o2) {
            return o2 - o1;
        }

    }

    public static class AComp implements Comparator<Integer> {

        // 如果返回负数，认为第一个参数应该拍在前面
        // 如果返回正数，认为第二个参数应该拍在前面
        // 如果返回0，认为谁放前面都行
        @Override
        public int compare(Integer arg0, Integer arg1) {

            return arg1 - arg0;

//			return 0;
        }

    }

}
